Research Paper Volume 9, Issue 9 pp 1957—1970

Figure 6. The G-quadruplex-specific antibody BG4 binds to a G-rich oligonucleotide derived from the promoter of Brca1. (А) The Cy5-conjugated BRCA1-G1 (G1), BRCA1-G2 (G2), and BRCA1-cont (cont) oligonucleotides (see Methods) were heat-denatured and then slow-cooled in the presence of K⁺ (KCl) to allow the formation of a secondary structure. 1.5 pmoles of each oligonucleotides (oligo) and 0 (a buffer alone), 30 or 50 ng of the BG4 antibody were incubated in a buffer, which contained 100 mM KCl. Note the bands that correspond to the free BRCA1-G1 (at the bottom) and the BRCA1-G1 bound to the BG4 antibody (at the gel top), both indicated with arrow heads. An asterisk marks the faint bands, which resulted from a loading dye. (B) The Cy5-conjugated BRCA1-G1 (G1), BRCA1-G2 (G2), and BRCA1-cont (cont) oligonucleotides were prepared in the presence of Na⁺ (NaCl). 1.5 pmoles of each oligonucleotides (oligo) and 0 (a buffer alone), 30 or 50 ng of the BG4 antibody were incubated in a buffer, which contained 100 mM NaCl. Note the bands that correspond to the free BRCA1-G1 (at the bottom) and the BRCA1-G1/BG4 complex (at the gel top), depictured with arrow heads. An asterisk marks the loading dye bands. (C) The Cy5-labeled BRCA1-G1 (G1), BRCA1-G2 (G2), and BRCA1-cont (cont) oligonucleotides were prepared in the presence of Li⁺ (LiCl). 1.5 pmoles of each oligonucleotides (oligo) and 0 (a buffer alone), 30 or 50 ng of the BG4 antibody were incubated in a buffer, which contained 100 mM LiCl. Note the bands that correspond to the free BRCA1-G1 (at the bottom) and a weak BRCA1-G1/BG4 complex (at the gel top), depictured with arrow heads. An asterisk marks the loading dye bands.